1) Field of the Invention
This invention relates generally to fabrication of semiconductor devices and more particularly to the removal of spin-on-glass (SOG) from wafer using an Edge Bead removal tool and more particularly to a pressure detecting system for monitoring the N2 pressure in a tank surrounding a solvent bottle.
2) Description of the Prior Art
Edge bead removal (EBR) is used to remove the spin-on-glass (SOG) at the ring side of the wafer edge, thus creating a cleaned ring. EBR may be necessary in process flows that incorporate post SOG processes when mechanical systems clamp both the front and backside of the wafer edge. Thick SOG on the edge is a potential source of particles where claimed. The solvent used for EBR is EL-100 (e.g., solvent is ethyl Lactate) made by Advanced chemical systems International, Inc (ACSI).
The inventors have found problems with current EBR tools. In particular, the EBR tools do not have adequate sensors and alarms to detect problems with the solvent delivery systems.
The importance of overcoming the various deficiencies noted above is evidenced by the extensive technological development directed to the subject, as documented by the relevant patent and technical literature. The closest and apparently more relevant technical developments in the patent literature can be gleaned by considering U.S. Pat. No. 6,024,249 (On) that shows a optical sensor for detecting bubbles in a SOG line.
U.S. Pat. No. 5,089,305 (Ushijima et al.) (assigned to TEL) shows a SOG/photoresist tool.
U.S. Pat. No. 6,010,570 (Motada et al.), U.S. Pat. No. 5,688,322 (Motad et al.) and U.S. Pat. No. 5,925,410 (Akram) show other SOG tools and processes.
It is an object of the present invention to provide a system for detecting problems with solvent delivery systems for edge bead removal (EBR) tools.
It is an object of the present invention to provide a system to monitor the gas (e.g., N2) pressure in a pressure tank that surrounds a solvent bottle for an EBR tool.
It is an object of the present invention to provide a system to monitor the gas (e.g., N2) pressure in a pressure tank that surrounds a solvent bottle for an EBR tool in a TEL MK-8 SOG machine.
To accomplish the above objectives, the present invention provides a system to monitor the gas (e.g., N2) pressure in a pressure tank that surrounds a solvent bottle for an EBR tool.
A preferred embodiment of the present invention will be described. The present invention provides a solvent delivery system for an edge bead removal tool (EBR). The invention is a system for detecting N2 leaks in a solvent pressure tank that surrounds a solvent bottle in an Edge Bead removal tool in a spin-on-glass coater. The invention comprises the following. A solvent bottle (e.g., EBR EL-100 bottle) is surrounded by a pressure tank (e.g., canister tank). The solvent bottle contains the solvent used in the EBR tool. The pressure tank is preferably comprised of a top, a bottom and an o-ring; wherein the pressure sensor detects when the o-ring is defective. A N2 gas supply is connected to the pressure tank and pressurizes the inside of the pressure tank with N2 gas. A pressure sensor is connected to the pressure tank. Wherein the pressure sensor senses the N2 pressure inside of the pressure tank. The pressure sensor is connected to an interlock circuit preferably by a line. The interlock circuit is connected to a system board by a line (interlock-board line). The system board notifies an operator when the pressure sensor detects an unsatisfactory N2 pressure condition inside the pressure tank. An unsatisfactory N2 pressure condition may be a low pressure below a low pressure limit or a high pressure above a high pressure limit. Alternatively, unsatisfactory N2 pressure condition may be a rate of pressure loss that is greater than a rate or pressure loss limit. The solvent bottle contains a solvent. A solvent delivery line connects the solvent bottle to a solvent buffer tank. A buffer solvent is in the solvent buffer tank. A solvent level sensor is on the solvent buffer tank. The solvent level sensor is connected to the interlock circuit. Wherein the system board notifies an operator when the solvent level sensor detects an unsatisfactory buffer solvent level in the solvent tank. A buffer solvent delivery line is connected from the solvent buffer tank to a nozzle over a substrate. The buffer tank preferably further comprises a drain valve. The interlock circuit is connected to the system user board by a circuit to board line.
Additional objects and advantages of the invention will be set forth in the description that follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of instrumentalities and combinations particularly pointed out in the append claims.